Abstract: For utilizing cotton stalk resources efficiently, a type of composite panels was produced by using extruded and oriented cotton stalk bunches as well as thermoplastic high density polyethylene (HDPE). Decomposition characteristics of cotton stalks was investigated by thermogravimetric analysis, and effects of density, HDPE loading, hot-pressing temperature and hot-pressing time on mechanical properties of composite panels were also analyzed by orthogonal experiment. Besides, intermeshing structure in the interface between cotton stalk fibers and HDPE was also investigated by scanning electron microscopy. The results showed that the superior hot-pressing parameters of producing composite panels were the following: density, HDPE loading, hot-pressing temperature and hot-pressing time were 0.8 g/cm3, 50%, 168℃, and 17 min, respectively. The modulus of rupture, modulus of elasticity and internal bounding strength of the composite panels reached 31.51 MPa, 4 561.25 MPa and 0.52 MPa, respectively. According to the above parameters, those mechanical properties can meet the standard values of particle board OSB/1.